1. Field of the Invention
The present invention relates to pipe connectors and more particularly to telescoping pipe connectors in which the end of one pipe engages in the end of the connecting pipe so that there is an overlap between the two.
2. Discussion of the Related Art
It is well known in the art that two pipes may be connected end to end using a flange type connection. In a typical flange type pipe connection, each pipe end has a flange formed on it, the two flanges abutting against each other when the two pipe ends are brought together. Fastening holes are formed in the two flanges around the entire periphery of the pipe ends through which fastening bolts extend to fasten the two flanges together. A seal with will normally be provided between the abutting faces of the two flanges to make the joint fluid tight.
Whilst this type of connection works well in some applications, due to the number of fastening bolts which are normally required with a large diameter pipe, disconnecting and reconnecting this type of joint, for example to replace or repair a damaged pipe section, can be very time consuming. As a result, flange type couplings are not suitable for use is harsh or remote environments due to the undesirableness of exposing workers to these environments for long periods of time.
An alternative pipe connector also known in the art which overcomes the problems associated with flange type connectors utilises a lock ring which extends across the end of the two pipes which are to be fastened so as to join them together. An example of this type of connector is shown in FIG. 1. With this type of connectors, one of the pipe members, referred to as the box member, has a cylindrical recess formed in its end which is sized to complement a cylindrical extension formed on the end of the other pipe member, referred to as the pin member, so that the end of the pin member may be slid into the end of the box member to form an overlapping connection therebetween. Usually, a seal such as an O-ring will be provided in the overlapping section.
The box and pin members both have circumferentially extending teeth formed on their outer surface proximate the connecting ends which complement circumferentially extending teeth which are formed on the inner surface of the locking ring. The locking ring is a slit ring which enables it to be expanded for fitting onto the end of the box member with its teeth engaged with the teeth on the box member to retain it thereon. The pin member is then driven axially into box member with sufficient power to expand the ring member through camming action between the teeth of the pin member and teeth of the locking ring until the pin member is fully engaged in the box member, whereupon the lock ring closes around the pin member with the teeth of the two members inter-engaged to prevent removal of the pin member from the box member.
In order to break the connection, the lock ring is expanded until its teeth are disengaged from the teeth on the pin member, whereupon the pin member may be axially withdrawn from the box member.
This connector is much easier and quick to connect and disconnect compared with the flange type connector. However, it has the problem that, in order to make and or break the connection, it is necessary to axially move one pipe end relative to the other in order to withdraw the pin member from the box member and also to withdraw the pin member from the collar. During initial assembly of a pipe string or line, or disassembly from one end, this is not an issue. However, in applications where is may be necessary to remove a pipe section from within a long pipe line, this is a problem as the neighbouring connections are the opposite ends of the pin, and box members will prevent the axial movement which is necessary to disconnect the pin member from the box member. As a result, this prior art connector is not suitable for applications where it may be necessary to break the pipe mid-section.